[rvf263]

Hi all,
I'm learning about volume and moles, V₁/n₁ = V₂/n₂

This is the problem:
"At a certain temperature and pressure, 8.00g of oxygen has a volume of 5.00L.
What is the volume after 4.00g of oxygen is added to the balloon?"

This is how I set it up and did it wrong....lol

V₁ = 5.00L                          V₂ = ?
n₁ = 8.00g O₂    n₂ = 4.00g O₂

I thought I had to change the grams to moles, so I came up with:
8.00g O2 x 1 moleO2 / 32.00g O2 = 0.25 moles O2.
4.00g O2 x 1 moleO2 / 32.00g O2 = 0.125 molesO2.

I plugged these numbers into:
n2 x V1 / n1 = V2

But I came up with 2.5L
The answer in the book is showing 7.5L

Can someone show me where I am going  wrong?

Thanks
Robert

[savoy7]

you've added 4 g to the 5 L

5L + 2.5 L (what the 4g O₂ = 7.5 L

[rvf263]

Thanks!